VIP Mail

Which email account are you referring to? Google, iCloud, AOL, Exchange, Outlook, Yahoo or any Other

You may get better and prompt responses if you may kindly provide the iPhone Model that you have and the iOS version if it is known to you and re-post.

What happens when you add VIP ?

How to use the VIP mailbox

In the Mail app, you can specify certain people as VIPs to help keep track of messages they send. Your VIPs have a star  next to the names in the message header. Your VIP mailbox is in the list of your mailboxes. 

If you can't find your VIP mailbox, make sure it's turned on. Go to Mail, tap Edit, then make sure VIP is selected in the list of mailboxes.

Add a VIP

1. Go to an email. 
2. Tap the sender’s name or email address in the message header. 
3. Tap Add to VIP.

Mail adds the VIP to your VIP mailbox. 

Alternatively

Change VIP alerts

1. Open Mail. 
2. Tap  next to VIP.
3. Tap Tap VIP....
4. Then select the Contact you want to set. If the contact has multiple email ids then all email ids of the contact will be treated as VIP mails. You mare calling a Contact as VIP not email id as VIP. Alternatively you can make an email id as favourite too.

Change VIP alerts

1. Open Mail. 
2. Tap  next to VIP.
3. Tap VIP Alerts.
4. Then select the alerts you want to set.

You can also go to Settings > Notifications > Mail, tap VIP, then select how you want to get VIP notifications.